Ca/Alq3 hybrid cathode buffer layer for the optimization of organic solar cells based on a planar heterojunction

Use of efficient anode cathode buffer layer (CBL) is crucial to improve the efficiency of organic photovoltaic cells. Here we show that using a double CBL, Ca/Alq3, allows improving significantly cell performances. The insertion of Ca layer facilitates electron harvesting and blocks hole collection, leading to improved charge selectivity and reduced leakage current, whereas Alq3 blocks excitons. After optimisation of this Ca/Alq3 CBL using CuPc as electron donor, it is shown that it is also efficient when SubPc is substituted to CuPc in the cells. In that case we show that the morphology of the SubPc layer, and therefore the efficiency of the cells, strongly depends on the deposition rate of the SubPc film. It is necessary to deposit slowly (0.02 nm/s) the SubPc films because at higher deposition rate (0.06 nm/s) the films are porous, which induces leakage currents and deterioration of the cell performances. The SubPc layers whose formations are kinetically driven at low deposition rates are more uniform, whereas those deposited faster exhibit high densities of pinholes

Large microwave plasma reactor based on surface waves

A microwave plasma reactor without magnetic fields has been designed for large surface treatment or deposition. Using the surfaguide principle, a 2.45GHz wave is coupled to the plasma created in a 12cm tube diameter surrounded by a metallic cylinder of 18.8cm diameter. The aim of this paper is to characterize this plasma, particularly the spatial homogeneity over the cross section. Argon and oxygen gases have been used. Pressure and microwave power were in the range 1 to 1000 Pascal and 200 to 2000Watt. Wave propagation study has shown that mainly a plasma mode (surface wave) of azimuthal hexapolar symmetry (π/3 periodicity) propagates. In argon gas, electron density (1011 to 1012 cm-3) and mean energy (1 to 3 eV) are locally measured by probes. Emission spectroscopy provides information on excited states distributions. They depend on the electric field distribution : azimuthally π/3 periodic and radially maximum near the wall due to the surface wave profile. Weakly modulated at high pressure, they are quite homogeneous at lower pressure due to the diffusion phenomenon. Actinometry has shown that the atomic oxygen density is rather homogeneous over the cross section whatever the pressure, which is promising for future surface treatment applications.Un réacteur plasma micro-onde sans champ magnétique pour le traitement de grandes surfaces ou le dépôt de couches minces, est présenté. Une onde à 2.45 GHz est couplée à un plasma créé dans un tube de 12 cm de diamètre entouré d'un cylindre métallique de 18.8 cm de diamètre. Ce papier présente une caractérisation du plasma, plus particulièrement pour l'étude de l'homogénéité spatiale du milieu sur sa section. Argon et oxygène ont été utilisés. Pression de gaz et puissance micro-onde ont été respectivement de 1 à 1000 Pascal, et de 200 à 2000 Watt. Une étude de propagation d'onde montre que le plasma est entretenu principalement par le mode plasma (onde de surface) à symétrie hexapolaire (de périodicité π/3). Dans l'argon on obtient des valeurs de densité et d'énergie des électrons de l'ordre de 1011 à 1012 cm-3 et de 1 à 3 eV. La distribution des états excités du plasma dépend du champ électrique : azimutalement π/3 modulée et radiallement maximum près du tube (onde de surface). Aux plus basses pressions, le phénomène de diffusion rend plus homogène la distribution de ces espèces. L'oxygène atomique est quant à lui assez homogène quelque soit la pression

Investigation of the ro-vibrational levels of H2_2/D2_2 molecules by VUV-absorption spectroscopy for the production of H−^-/D−^-negative ions for fusion application

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Investigation of the ro-vibrational levels of H2_2/D2_2 molecules by VUV-absorption spectroscopy for the production of H−^-/D−^-negative ions for fusion application

https://publications.aob.rs/102/pdf/spig2022-23-8.pdfInternational audienc

ECR–Driven Negative Ion Sources Operating with Hydrogen and Deuterium

International audienceThis chapter is devoted to the fundamental principles of electron cyclotron resonance (ECR) sources yielding H− and D− negative ions. Initially, it provides a brief but meaningful overview of the theoretical framework for ECR plasmas along with commonly employed experimental configurations, unveiling thus the distinct features of this special category of high-frequency electrical discharges. It is highlighted that it is not aimed to cover the vast field of microwave discharges (e.g., microwave discharges in waveguides and resonators), nor the vast field of wave-heated discharges (e.g., helicon discharges and surface wave discharges). Such an attempt would be a utopia within the frame of one book chapter. Therefore, Sect. 12.1 of this chapter presents elementary physical quantities of plasmas, related to the ECR idea, and an idealized, simplified concept of the complex wave propagation in ECR plasmas where the wave energy absorption is achieved through collision-less heating mechanism (Firdman and Kennedy, Plasma physics and engineering. New York: Taylors & Francis Books Inc., 2004;Williamson et al., J. Appl. Phys. 72:3924, 1992). The presentation concerns low-pressure, nonthermal, and nonequilibrium plasmas. Then, the core of this review is devoted to the targeted application of ECR heating to negative ion sources operating with molecular hydrogen (H2) and deuterium (D2). Once again, the relatively vast field is impossible to be treated in the context of this chapter, but the authors hope that the cited sources are worthy representatives. Fundamental processes governing the H− and D− ion production (destruction) are summarized in Sect. 12.2, while the extended Sect. 12.3 provides recent experimental results from ECR-driven sources and comments on them in detail. Diagnostic techniques applicable to these sources are also mentioned at the beginning of Sect. 12.3. This chapter closes with Sect. 12.4, where additional ECR sources are touched upon and negative ion-extracted currents from different sources are compared. The review is throughout supported by future-proof classic or up-to-date bibliography for further reading

Chemical and Electrochemical Regeneration of InP after GD-OES/XPS Profiling Experiments.

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